Motion Study Springs 1

[heritagesurf7]

Hey,

I've tried searching google and using the SW help guide, but I can't figure out how these springs work in motion study. I have a rubber bladder that I want to simulate expansion and contraction using springs in the basic motion animator. I was told if I had three versions of the part, one full, midway, and empty, the spring would cycle between them. I don't think that's correct though. Any help? Thanks

 

[Gupta65]

No that is not what spring are meant for in animation.

Check these posts on spring animations and model your parts accordingly

How To Animate a Spring (

http://www.solidworks-apac.com/2009/12/21/how-to-animate-a-spring/)

How to animate a spring – Part 1 (

http://gupta9665.wordpress.com/2009/05/25/how-to-animate-a-spring-1/)

How to animate a spring – Part 2 (

http://gupta9665.wordpress.com/2009/06/01/how-to-animate-a-spring-2/)

Deepak Gupta
SW2009 SP4.1
SW2007 SP5.0
MathCAD 14.0

 

[Cockroach]

Absolutely outstanding. I have been attempting this for a long time, having drawn springs using a helix in the Sweep command. I knew there was something missing, but being relatively new to the Motion program, never had time to investigate further. Thanks for the insight Gupta, incredible animation!

Listen, what is the secret for Torsion Springs? I have a Check Valve that I want to animate like the Compression Spring. I think similar to what your Lesson has done? I have drawn the helix part of the Torsion Spring Body and then using two separate legs, spliced them to the end of the helix. I then simply Sweep the path using the cross sectional diameter of the Torsion Spring. Same mistake I think as the Compression Spring?

Again, thanks for your time in making the animation showing the Spring Motion. Super job!

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[steinmini]

I'm not sure if this can help, it helped me when I needed it.

http://youngdutchdesign.com/pressuresprings-in-solidworks

 

[heritagesurf7]

SOLVED! Hey thanks for all the help everyone. I followed one of the guides. In the end, I had to create to end peices for the bladder, and had a line connecting them whose length depended on the position of the endpoints. Then, I applied a linear motor and as the end points were pushed together, the connecting line shrank. That's the basic idea used.

It all had to be done within the assembly I was working on. You can't create a dynamic relationship, and then import the part into an assembly and still have the dynamic changes. The part that changes needed to be built within the final assembly. Thanks again.

 

[Cockroach]

I am following Gupta's assembly model, bolt-spring-nut, the spring in dynamic motion. The Spring is drawn correctly and will display compression/extension using Instant3D.

But in the assembly, I cannot get the dynamic relationship for the variable spring length to mate correctly with the nut. When the "coincidence" relationship is added to the free end of the spring and face of the nut, the nut becomes "fixed" and does not float in the model.

What am I missing?

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[SnowCrash]

For a real fun time, replace the straight line in the 3D axis sketch with a wandering spline!
"Knotted up"

--
Hardie "Crashj" Johnson
SW 2010 SP 2.1
HP Pavillion Elite HPE

 

[Cockroach]

I managed to solve my own problem. It turns out that the order of child parts in the assembly is very important as is the method for modeling the Spring component itself.

Essentially you need to model the Spring using a helix specified by "height and pitch". This is imported into the assembly model AFTER the Nut and Bolt items are mated, obviously the Nut is mated dynamically as a "screw" using the exact pitch of threading. I found it extremely helpful to immediately dimension the face-to-face length between the bolt and nut. This is the important part, you should be able to thread the nut and regenerate the model to arrive at a new face-to-face length.

After importing the Spring and placing correctly on the shank of the Bolt, equations are used to provide a variable pitch. Order of equations is important to avoid nesting issues. First equation is to make the overall length dimension of the Spring equal to the face-to-face distance previously dynamically dimensioned. The second equation is to make the pitch equal to the overall length divided by the number of spring coils.

You will need to regenerate the model after moving the nut, which now is free to spin on the threaded bolt. The model correctly sizes the distance between faces of the nut and bolt, places the spring between them and regenerates with the correct number of coils.

The AutoCAD inventor folks call this "adaptive geometry". Clearly it is possible to use my process in SolidWorks models for dynamic simulation of a spring.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada